Ultrasonic transducers are known that have a laminated construction, enabling the formation of multiple, generally circular ultrasonic transducers (e.g., up to about 80 or more) in an ultrasonic transducer array. Such ultrasonic transducers can include first and second insulative retaining layers, and a vibrator film layer sandwiched between the respective first and second retaining layers. The first retaining layer can include a first plurality of circular apertures formed therethrough and the second retaining layer can include a second plurality of circular apertures formed therethrough, in which the second plurality of apertures is substantially in registration with the first plurality of apertures. Such ultrasonic transducers can further include first and second cover portions, and the combination of the first retaining layer, the vibrator film layer, and the second retaining layer can be sandwiched between the first and second cover portions.
In the ultrasonic transducers described above, the side of the vibrator film layer facing the first retaining layer is typically unmetallized, and the opposite side of the vibrator film layer facing the second retaining layer is typically metallized. The ultrasonic transducer can further include a plurality of circular, electrically conductive backplates and a plurality of electrically conductive coil springs, which can be disposed between the first cover and the vibrator film layer in substantially the same plane as the first retaining layer. Each circular backplate is substantially in registration with respective circular apertures formed through the first and second retaining layers. Further, each circular backplate typically includes a plurality of grooves, such as V-shaped grooves or trapezoid-shaped grooves, formed on surface thereof. The plurality of grooves are typically machined, etched, or stamped on the backplate surface, and are typically fabricated to have sharp corners and/or edges and straight sides. Each coil spring is disposed between a respective backplate and the first cover. The coil springs are both mechanically and electrically connected to respective backplates and the first cover, which has an electrically conductive surface. The first cover portion, the coil springs, the respective circular backplates, and the combination of the first retaining layer, the vibrator film layer, and the second retaining layer, are configured to cause the coil springs to urge the circular backplates against the unmetallized side of the vibrator film layer through the respective circular apertures.
With further regard to the ultrasonic transducers described above, the combination of the electrically conductive first cover, the coil springs, and the circular backplates forms a first electrode, and the metallized side of the vibrator film layer forms a second electrode. The ultrasonic transducers are configured to allow a voltage to be applied between the first and second electrodes, thereby generating an electric field between the vibrator film layer and the backplates that causes the film to be attracted to the respective backplates. In the event the voltage applied between the first and second electrodes is AC, the film can vibrate, in a transmitting mode, to generate compression waves at sonic or ultrasonic frequencies. In a receiving mode, incoming acoustic waves impacting the ultrasonic transducer are converted to a voltage waveform.